The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Datacenter utilization is generally poor because the datacenter infrastructure is constructed for the highest capacity that is forecasted. Initially the datacenter operates well below the forecasted capacity. Adding power/load capacity to a conventional datacenter is inherently risky because of the potential to put a fault on the system and take down live servers. Additional power sources must be provided to a power bus that supplies racks of servers and/or storage arrays.
Referring now to FIG. 1, a first bus architecture 10 is shown to include an AC signal source 12 such as a utility. An output of the AC signal source 12 is connected by one or more circuit breakers 14 and a transformer 16 to an uninterruptible power supply (UPS) 20 and one or more branch circuits 22. The branch circuits 22 may be used to supply non-essential loads such as lighting.
The UPS 20 provides standby power to essential loads in the event that the AC signal source 12 is unavailable. The UPS 20 typically includes an AC/DC converter 24 to convert the AC input to a DC signal. The AC/DC converter 24 is connected to a DC/DC converter 28 and a DC/AC converter 30. The DC/DC converter 28 is connected to an array of batteries 34 that are charged when the AC signal source 12 is available. When the AC signal source 12 fails, the array of batteries 34 provide backup power to the essential loads for a predetermined period. The DC/AC converter 30 is connected to a first AC bus 36A.
A plurality of loads generally identified at 40 may be connected to the first AC bus 36A. Examples of the loads include server racks 44 and/or storage arrays. Each of the server racks 44 typically includes a switch or router, a plurality of servers and/or arrays of disk drives. Other datacenter loads include lights, fans and pumps for cooling, air conditioning equipment, etc. The server racks 44 are typically connected by a circuit breaker 46, an AC/DC converter 48 and a DC/DC converter 50 to the server racks 44. In some examples, AC power is delivered to the server racks 44 and then within each server or server chassis, AC/DC and DC/DC conversion is performed. In other words, the server racks 44 include the AC/DC converter 48 and the DC/DC converter 50 in some examples.
A second AC bus 36B with a similar architecture can be provided. In some examples, some of the loads 40 may be connected to the first AC bus 36A and the second AC bus 36B. Example loads include motors and AC drive circuits for cooling pumps or other devices.
As can be appreciated, when additional loads need to be connected to one or both of the first and second AC busses 36A and 36B, additional power supply capacity is also needed. However, issues such as synchronization of the AC frequency of additional AC signal sources added to one or both of the existing AC signal sources 12 may cause system faults. Datacenters typically have uptime constraints and cannot be taken off-line due to system faults. Since it is difficult to safely add additional power sources to this bus architecture without problems, the power bus is typically sized a lot larger than necessary when originally constructing the datacenter to deliver the largest amount of power that is anticipated to be needed in the future. This increases the overall cost of installation without an equivalent source of revenue until load capacity grows.
Referring now to FIG. 2, a DC bus architecture 50 that can also be used for datacenters is shown. In this architecture, an AC power source 52 such as a utility is connected by one or more circuit breakers 54 and a transformer 26 to an AC/DC converter 58. The AC/DC converter 58 is connected to a first DC bus 62A. An uninterruptible power source (UPS) 64 includes an array of batteries 66 that is connected by a DC/DC converter 68 to the first DC bus 62A to provide power for a predetermined period in the event that the AC power source 52 is unavailable. A plurality of loads generally identified at 74 is connected to the first DC bus 62A.
A second DC bus 62B having a similar architecture as the first DC bus 62A can be provided. In some examples, some of the loads 74 may be connected to both the first DC bus 62A and the second DC bus 62B.
When increasing capacity, it is difficult to add additional AC signal sources to provide additional power on the DC bus due to synchronization of the AC signal sources and other issues.